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  #91  
Old 09-23-2019, 06:34 PM
Joe
 
Join Date: May 2019
Location: Connecticut
Posts: 92
Hi Funola...thanks for your advice...it's so easy to pull injectors (now that I've done it about two dozen times, not by choice lol!), it makes sense to watch them...btw...the Monarks seem to have a pretty tight spray plume...fanning out to about 5-10mm...is that what you've seen? Seems tight to enhance hitting the ball for supplemental dispersion. On the rebuild side, my old injectors weren't rusty inside, and I did use a torque wrench...I think it was 25ft-lbs if memory serves correct. I had to do this (lapping and re-assembly) like three times before they stopped leaking...was confusing because it acted like a leaky return hose. those btw, seem to have to be clipped every time you pull them off to seal, or use a new section. What oil do you use? I've been using Rotunda 15W-40...

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  #92  
Old 09-24-2019, 12:57 PM
gmog220d's Avatar
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Location: Albuquerque, New Mexico, USA
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Quote:
Originally Posted by inzgary View Post
Here is one similar instance I found: Pre-Chamber Ball Came Loose
That was a 220 so the non turbos also had the same pre chamber design. Add going 70 mph down the highway and the pressures going in and out of the pre chamber are likely high enough to blow the tip away. My theory is that is caused by a streaming injector. The metal ball starts burning, breaks loose, and rattles around ultimately creating a check valve of the pre chamber.
That's my thread linked to above. Given my experience I tend to agree with inzgary and others that your problem, Joe, started with a leaky injector permitting too much fuel to enter the pre-chamber. As I came to learn, thanks to other helpful and patient members on this form, too much fuel injected will burn things up, like causing the ball to come loose, deforming the glow plug tip, etc., and perhaps eventually leading to a major blow out like you experienced.

My troubles were caused by my mucking around with the IP governor. I ended up with a rich condition and it took 2000 miles of driving to reach the point shown in my thread. What happened to your engine is an extreme version of what happened with mine. In my engine, because the trouble linked back to the IP, every cylinder was affected, but it was #4 where things reached a breaking point. I got lucky - the pre-chamber did not come apart and drop pieces into the combustion chamber. My situation played out more slowly because the problem was not caused by the injector itself, the rich condition in my engine was lesser than it would have been if it were the injector dribbling into the pre-chamber.

I am embarrassed to admit that my '74 240D is still off the road, the IP still sitting on the bench waiting to be installed. Our "new" property in the mountains has caused a shift in my priorities, and wrenching on my extra vintage car has moved way down the list. At least it's sitting in a garage, protected from the elements. I think I'll get back on this project in the near future, though. I'd like to drive it!

Anyway, I believe that injector maintenance should be a high priority for these engines, especially in a car that's "new" to us. Pulling the injectors and having them checked and repaired is one of the first things to do, unless you know for certain the injectors have been worked on in recent past. I also like to pull them every couple years and have them popped by the local shop. I never had a problem until I messed up the IP's fuel output. Lesson learned.
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  #93  
Old 09-24-2019, 01:00 PM
funola's Avatar
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Quote:
Originally Posted by PreferVintage View Post
Hi Funola...thanks for your advice...it's so easy to pull injectors (now that I've done it about two dozen times, not by choice lol!), it makes sense to watch them...btw...the Monarks seem to have a pretty tight spray plume...fanning out to about 5-10mm...is that what you've seen? Seems tight to enhance hitting the ball for supplemental dispersion. On the rebuild side, my old injectors weren't rusty inside, and I did use a torque wrench...I think it was 25ft-lbs if memory serves correct. I had to do this (lapping and re-assembly) like three times before they stopped leaking...was confusing because it acted like a leaky return hose. those btw, seem to have to be clipped every time you pull them off to seal, or use a new section. What oil do you use? I've been using Rotunda 15W-40...

I do not remember what the spray pattern looks like since it was while ago. There are instructions that came with the Monarks with spray pattern diagrams I believe.

I don't recall having to lap the injector halves with abrasives. I think I used brown paper bags on a piece of glass, spray it with WD-40 and rubbed the halves on it till the grime is gone and that's about it.

Trick to find where the injector is leaking: Twist some toilet paper into a rope. Starting from the top of the injector, wrap a coil at the injector nut, one at the nipples, one at the halves, one at the head. Start the engine and watch which one gets wet and there's your leak.

I used mostly Shell Rotella 15W40 dino and whatever other brands that are on sale which included Delvac, Chevron, SuperTech etc
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  #94  
Old 09-28-2019, 01:46 AM
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Sorry you were cheated out of a 1M mile engine. Me too when my 1985 CA 300D engine failed at 330K miles ~12 yrs ago (probably posted w/ photos). I think it was the earlier non-turbo engines which more commonly made it to 1M. In my case, #1 cyl had the piston's top beat up from something hard bouncing around. Some imprints looked like perhaps a small ball bearing, but no idea how one could have gotten in after the air filter. Only ones I know are in the vacuum pump, so how could they get up to the valve cover vent? Maybe lifted by the timing chain, flung off, and then blow-by carried them? I don't recall that vacuum pump having missing balls on the roller (used it later). The pre-chambers and glow-plugs all looked fine (other than #1 prechamber had pocks on the outside from the bouncer). Two other pistons had chunks missing around the ring grooves but no marks at the top. Prior to this, compression had dropped to ~250 psig in all cylinders and it needed a block heater overnight to start on <40 F mornings. A year prior, I heard something rattling around, like a ball bearing inside the engine. Opened the hood, couldn't find anything, it then went away. When it recurred, I kept driving slowly and after 3 miles when I lifted the pedal, the engine died, then wouldn't even crank (seized). I pulled the head to find above.

I lucked out. I first bought a 1984 300D w/ "cracked frame" after a theft/curb crash for $400 on craigslist from a guy just 1 mile away. Intended to use that engine and part-out the car, but then found the damage was just to the K-frame and the shop's weld-repairs (while ugly) were still OK. It had just cracked at the LCA pivot bracket on L side. The owner assumed their repair had failed so gave up. I repaired it (1st time welding w/ $90 HF flux-wire), adding a support strap around the crack. My son used that car thru college, med school, and still has it finishing his residency. BTW, the shop's shoddy weld @ top of K-frame failed ~4 yrs later 600 mi away in San Diego, but I was able to drive the car home (cleverly secured 2 LCA's together w/ chain, drove perfectly straight) and repaired that, welding an L-bracket across the top to secure it better than the factory's few spot welds. I later repeated that on the other side (to be safe), when parts were off making it accessible (shop had tried to weld w/o elbow room).

Soon after getting the 1984 road-worthy, I found a used engine on craigslist for $300 w/ starter (worth $100). Turned out to be perfect. Indeed the camshaft appeared new w/ a clean paint stripe seen thru the oil fill hole. Seemed suspect since I bought from a mechanic who spoke little English and worked out of a horse barn w/ mostly VW Bug stuff around. I later measured compression >400 psig in all cylinders (like new). I think a 1982 engine. I then had all the accessories from the 1985 engine for the future (vac pump, ... and have used many). I later installed the 5 injectors from the 1985 engine, after pop-testing them. The reason was that the 1982 engine had 3 injectors which were for a non-turbo (popped at ~1600 psig), though it ran fine. The 1985 injectors just needed slight shimming to hit factory pop (1950 psig) and the spray pattern looked good (no leaks nor streamers), so I don't think bad injectors caused the failure. After ~10 yrs driving w/ the 1982 engine, I am having issues w/ overheating, but that is another saga (failed head gasket or cracked head?, tried everything else). All-in, I spent ~$700 plus ~$100 for parts to make a pop-tester and fixed my 1985 plus got a second 300D, plus a lot of my time (wife doesn't value that).

Re rebuilt engines, I see them online for $8500 at the SoCal place which is about the only source. I have seen new pistons for $550 each, but not in a while. A set of 5 sold for ~$1500 on ebay a few years ago. In contrast, the non-turbo pistons are almost affordable, but don't get those by mistake. I got a set of 5 used pistons for ~$100 from member Rollguy here. I started rebuilding the failed engine years ago. I replaced the cast-iron liners (posted how), but haven't taken the block to a machine shop to surface the head and hone the cylinders to the pistons. No need to spend those bucks yet. ~7 yrs ago an OM617.952 sold on ebay for ~$2000. The seller said he was an engineer who rebuilt it carefully (perhaps for a car he no longer owned) and it looked nice in shiny paint. Perhaps someone here bought it. Anyway, you fixed your problem and we all appreciate your sharing and details.
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Last edited by BillGrissom; 09-28-2019 at 02:12 AM.
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  #95  
Old 09-28-2019, 07:57 AM
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Great tips and suggestions.
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  #96  
Old 09-28-2019, 11:09 AM
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Join Date: Jan 2012
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Quote:
Originally Posted by funola View Post
Start the engine and watch which one gets wet and there's your leak.

And to expand on this, never ever check for a leak with your hands. Getting injected with oil is a major medical emergency that needs immediate hospital attention. Not in a minute, NOW.
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  #97  
Old 09-28-2019, 02:20 PM
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if anyone is interested kent just found another blown prechamber on the same engine!


part 6 digby:


https://www.youtube.com/watch?v=4_xFiIVRY6w
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  #98  
Old 09-28-2019, 04:28 PM
Squiggle Dog's Avatar
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Quote:
Originally Posted by BillGrissom View Post
Sorry you were cheated out of a 1M mile engine.
This made me chuckle. Mine has about 350,000 miles on it, so here's hoping I don't get cheated out of my 1,000,000 engine, either.
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  #99  
Old 09-28-2019, 04:54 PM
funola's Avatar
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Quote:
Originally Posted by christuna View Post
if anyone is interested kent just found another blown prechamber on the same engine!


part 6 digby:


https://www.youtube.com/watch?v=4_xFiIVRY6w
That's even more unbelievable! Missing tips on glow plugs and blown pre-chamber tips on 2 cylinders w/o wrecking the engine! Go buy some lottery tickets!
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  #100  
Old 09-28-2019, 11:31 PM
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You know I’ve been watching those digby videos and I’ve been wondering how nobody noticed the blown prechambers during compression testing. The PO had it compression tested and Kent did it multiple times.

All I can say is the videos (and this thread) have worked on me. My cars run well but I’m ready to send my injectors to greazer or buy one of Kent’s pop testers.
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  #101  
Old 09-29-2019, 05:10 PM
E300d 1995
 
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I lost a good low mileage 2500HD that I had due to what I suspect was the Chevy dealer mechanic not being clean enough during replacement of the injection pump under warranty. After the repair and only about 8 miles towards home, the engine started to sound like a 10 pound sledge was hitting repeatably. It was unbelieveably loud. I killed it immediately and had a tow truck take it back to the dealer. Dealer, of course, said it wasn't their fault. I had to pay for the #2 injector to be replaced. About a 100 miles later the engine blew that cylinder. Glow plug tip had been burnt completely off plus the piston was shattered for #2 cylinder. Probably no more than a 30 seconds of really loud hammering due to failed injector.

This site has some informed info on injector failure and resulting damage:

Diesel water damage - Karmakanix VW, Audi & Porsche

Title is misleading damage can occur from crud and/or a little water in fuel that reaches the injector(s) and messing up the spray pattern.
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  #102  
Old 10-03-2019, 01:56 PM
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I suppose it shouldn't really cost too much to replace the nozzles and then have them tested to confirm all is functioning correctly? Or are we talking about replacing the entire injector itself?
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  #103  
Old 10-07-2019, 02:49 AM
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PreferVintage you're now famous


part 7 digby:



https://www.youtube.com/watch?v=5uyTEyqJRYc

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